The broad, long term objective of the research proposal is to examine whether the potential impact on coronary heart disease (CHD) risk reduction of an NCEP/AHA Step One Diet may be currently underestimated because of an overemphasis on the avoidance of fat and cholesterol and an underemphasis on the inclusion of plant-based foods. Oxidative stress, as estimated by LDL oxidizability, is an important determinant of atherosclerotic potential. The specific aims are to examine LDL oxidizability in adults on a plant based NCEP/AHA Step One Diet versus adults on a diet of commercially available reduced fat products. In a clinical trial using parallel design, seventy adults with moderately elevated LDL-cholesterol (LDL-C 130-190 mg/dL) were randomized to one of the two diets for four weeks. All meals were provided, and the composition of the two study diets were determined by chemical analysis. The applicant will examine the susceptibility of LDL to oxidation in serum samples obtained at the end of the study period in both groups by measuring the lag phase of conjugated diene formation induced by Copper++.